共查询到19条相似文献，搜索用时 140 毫秒
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通过对北京西山下苇甸剖面中典型风暴成因竹叶状灰岩的野外实测和镜下薄片分析，明确了59套风暴沉积特征，确定了风暴沉积序列并建立了陆表海风暴作用沉积模式，主要取得如下认识：(1)北京西山下苇甸寒武系共有泥晶灰岩相、含砾屑泥晶灰岩相、颗粒泥晶灰岩相和泥晶颗粒灰岩相4种岩相类型。(2)鲕粒灰岩-砾屑灰岩型序列发育原地型风暴岩，泥岩和粉砂岩-砾屑灰岩型序列发育近源型风暴岩，泥晶灰岩-砾屑灰岩型序列发育远源型风暴岩。(3)原地型风暴岩发育侵蚀面，砾屑含量高，长短轴比大；近源型风暴岩砾屑定向性好，可见递变层理；远源型风暴岩基质含量高。(4)竹叶状灰岩沉积在陆表海背景下的潮下带，原地型、近源型和远源型风暴岩沉积范围以正常浪基面和风暴浪基面为界，距风暴中心距离和搬运距离依次增加。本次研究不仅补充了下苇甸寒武系的风暴沉积记录，而且为该时期的古环境研究提供了证据。 相似文献
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再论安徽沿江地区中二叠统栖霞组砾屑灰岩的成因 总被引：1，自引：0，他引：1
安徽沿江地区中二叠统栖霞组地层厚度大,有机质含量高,保存条件良好,其广泛发育的砾屑灰岩也是人们重点关注的对象。但对砾屑灰岩的成因一直存在不同的观点,这对下扬子地区二叠纪古地理恢复及油气勘探等无疑是一种制约。因此,确定栖霞组砾屑灰岩的成因及沉积相意义重大。根据砾石的颜色、含量、产出形态、粒径和圆度等,本文将栖霞组砾屑灰岩分出四种不同类型。综合国际上对砾屑灰岩的成因认识及前人对本区的研究成果,并结合本文研究,对栖霞组砾屑灰岩的成因进行深入讨论。讨论结果显示,砾屑灰岩应为斜坡沉积产物。另外,由于斜坡坡度的差异,分别发育不同的砾石形态、砾石与基质的组合及岩相特征。栖霞组砾屑灰岩的斜坡相沉积可以进一步分为斜坡上部、斜坡中部和斜坡下部。 相似文献
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西天山阿吾拉勒阔尔库一带早石炭世阿克沙克组以海相碳酸盐岩夹碎屑岩为主,发育典型风暴成因的竹叶状砾屑灰岩。风暴沉积构造主要有风暴侵蚀构造、风暴撕裂构造、风暴浪构造、风暴涡流构造及风暴期后快速沉积构造等。已识别出的风暴沉积类型有具块状层理的竹叶状砾屑灰岩,具递变层理的砾屑灰岩和砾屑砂岩,具丘状、洼状交错层理和平行层理的砂屑灰岩及生物碎屑砾屑粉砂质灰岩,具平行层理的砂屑灰岩、长石岩屑砂岩,具波痕交错层理的砂屑灰岩和砾屑粉砂质灰岩,具水平层理的粉屑灰岩和具块状或水平层理的生物碎屑砾屑粉砂质灰岩。新发现的风暴沉积,说明早石炭世该地区处于低纬度带陆棚浅水沉积环境,因而对于分析西天山石炭纪的古地理、古气候、古构造及板块的运动规律具有重要意义。 相似文献
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碳酸盐台地的类型、特征和沉积模式--兼论华北地台寒武纪陆表海-淹没台地的沉积样式 总被引：2，自引：0，他引：2
随着对现代碳酸盐沉积环境的系统调查和解释、以及对碳酸盐沉积原理认识的深化,自20世纪60年代,一系列碳酸盐沉积相模式得以建立,其中最引人注目的是Wilson和Tucker的工作。但在镶边陆棚及缓坡模式得到了广泛认可和使用的同时,对陆表海和淹没台地型沉积未能予以足够的重视。与过去相比,现今的海平面是相对较低的,因而没有出现陆表海广泛发育的情况。但在漫长的地质历史时期,陆表海曾经覆盖了广泛的克拉通区域,是碳酸盐沉积最重要的场所之一。本文在系统总结前人成果的基础上,将用于描述大尺度碳酸盐岩沉积环境的碳酸盐台地分为镶边陆棚、缓坡、陆表海、孤立台地和淹没台地5种类型分别描述,并重点强调了陆表海和淹没台地的沉积模式。华北地台寒武系大面积分布的潮坪沉积、鲕粒滩相灰岩和竹叶状风暴砾屑灰岩,以及频繁出现的台地淹没事件,为阐明陆表海和淹没台地的沉积提供了绝佳实例。这些实例和研究表明了碳酸盐沉积环境的多样性和沉积过程的复杂性,以及将今论古的困难性,从而为碳酸盐沉积原理的认识和沉积环境的解释提供新认识和新思路。 相似文献
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上扬子地区晚二叠世晚期及早三叠世早期异常碳酸盐岩可以按成因分为3大类：A类-生物成因
的异常碳酸盐岩,B类-非生物成因（化学及水动力成因） 的异常碳酸盐岩,C类-生物、水动力及化学等复
合成因的异常碳酸盐岩;还可进一步识别出8个具体类别,包括微生物岩、角砾状灰岩、扁平砾屑灰岩、条带
状灰岩、薄板状、纹层状泥质灰岩、鲕粒碳酸盐岩及a、b型蠕虫状灰岩。近乎极端的古海洋环境和古气候条件
是P/T转换时期以错时相为主的异常碳酸盐岩得以发育并作为早三叠世重要沉积类型的基础;P/T生物大灭绝
事件发生以后,底栖动物对海相沉积层表面的破坏几乎停止,海洋洋流近乎停滞,与此同时表层海水饱受季风
与飓风风暴的侵扰,分布在生物礁或浅水碳酸盐岩台地之上的透光带菌藻生态系统生长为具有一定抗浪能力的
微生物岩,频繁的风暴对海底的影响使得同生期弱固结的碳酸盐软泥被打碎而形成同生砾屑,一定的古地形坡
度又加剧了风暴为诱因的碳酸盐沉积物重力流的发育;此外,碳酸钙过饱和的海水可以使得碳酸盐直接化学沉
淀于海底,同时巨型季风带来的黏土和粉砂与碳酸盐化学沉积共生,这一系列的过程发生于早三叠世早期特殊
的古环境中,造成了上扬子地区多种多样的异常碳酸盐岩沉积。 相似文献
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我国的碳酸盐风暴岩丰富多样,但前人对不同环境风暴岩的沉积作用、沉积序列和沉积模式的总结还不够完善.山东省中部上寒武统炒米店组碳酸盐风暴岩发育频繁,分布广,提供了全面分析风暴沉积作用的理想场所.基于该区详实的露头观察,可识别出冲刷面、渠模、丘状交错层理等典型的风暴沉积构造,以及砾屑灰岩、递变层理含砾砂屑灰岩-砂屑灰岩、纹层状粉-砂屑灰岩等风暴岩类型.根据砾屑颜色、磨圆度、排列方式、支撑结构、充填物等岩石学特征,研究区首要发育的砾屑灰岩可被细分为紧密堆积棱角状砾屑灰岩、基质支撑砾屑灰岩、砂屑支撑砾屑灰岩、水平-叠瓦状砾屑灰岩和放射状排列砾屑灰岩5种岩相类型,其分别归属于台前缓坡带原地-近源堆积、碎屑流、高密度-低密度浊流、风暴砾滩和风暴涡流沉积.对台前缓坡、台地边缘和开阔台地等不同环境的风暴沉积序列进行了归纳,建立了缓坡型碳酸盐台地风暴沉积的综合模式,并指出研究区频繁的风暴作用与全球气候变暖、海平面上升以及地震活动存在密切联系.研究表明较多台地边缘发育的大型渠模构造,其充填砾屑呈放射状排列,指示了渠模的风暴涡流成因 相似文献
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湘西吉首地区寒武系碳酸盐岩沉积环境的初步探讨 总被引：1，自引：0，他引：1
本文通过岩石组分、组构、沉积构造及岩石共生组合分析,认为湘西吉首地区寒武系碳酸盐岩主要形成在浅水碳酸盐台地.各类灰岩中的内碎屑、藻团粒、生物碎屑及低能鲕粒等颗粒类型广泛发育,白云岩中的残余组分及上述两类岩石普遍含有数量不等的陆源物并具各种流动浅水特征的沉积构造标志等事实支持了这一认识.与上述岩石共生间隔发育的砾屑灰岩(云岩)多属风暴沉积类型,在台地边缘斜坡上部-浅海陆棚环境中形成. 相似文献
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华北地台上寒武统崮山组出现了大量的竹叶状灰岩。通过对山东唐王寨剖面崮山组的系统研究,识别出页岩、疙瘩状泥晶灰岩、泥质条带泥晶灰岩、薄层状泥晶灰岩、生物扰动泥晶灰岩、颗粒质（生物碎屑）泥岩-泥质颗粒岩、含交错层理鲕粒灰岩及竹叶状灰岩8种岩石类型,这些岩石类型组成了页岩盆地、深潮下带及浅潮下带岩石组合。竹叶状灰岩中砾屑和基质的特征及其沉积序列,表明砾屑和基质的来源多样并且在不同的沉积环境中其成因具有多样性。据此总结出崮山组竹叶状灰岩具有4种可能的成因类型：1）竹叶状灰岩中砾屑和基质可能均为原地形成或者仅有短距离的搬运过程;2）竹叶状灰岩中砾屑和基质可能均为近岸形成并经历了长距离的搬运过程,或者竹叶状灰岩的沉积环境经历了海平面的突然升高;3）竹叶状灰岩中基质可能来源于近岸未固结的鲕粒和生物碎屑及原地的灰泥,与原地破碎生成的砾屑和灰泥等混合沉积;4）竹叶状灰岩中砾屑可能来源于远岸的固结的泥晶灰岩,并经搬运作用与原地未固结的灰泥及骨架颗粒等基质混合沉积。 相似文献
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华北地台在晚寒武世为一个较为典型的缓坡型台地,在其北部的地层中以发育风暴砾屑灰岩及生物丘灰岩著称,包括崮山组、长山组和风山组;在该套地层中,深缓坡相泥岩和泥灰岩、与浅缓坡相颗粒灰岩和泥粒灰岩一起构成若干潮下型碳酸盐米级旋回,这些米级旋回本身即为有序的异成因岩相序列而成为基本工作单元;在长周期三级层序中米级旋回形成有序垂直叠加形式,反映了三级层序本身是一个与三级相对海平面变化相关的环境加深和环境变浅过程所形成的沉积相序列。根据这些特征在华北地台北部晚寒武世地层中可识别出4个三级层序。从北向南,相变为一套白云岩; 相似文献
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This paper focuses on the formative processes of limestone pseudoconglomerates in the Gushan and Chaomidian Formations (Late Cambrian) of the North China Platform, Shandong Province, China. The Gushan and Chaomidian Formations consist mainly of limestone and shale (marlstone) interlayers, wackestone to packstone, grainstone and microbialite as well as numerous limestone conglomerates. Seventy‐three beds of limestone pseudoconglomerate in the Gushan and Chaomidian Formations were analysed based on clast and matrix compositions, internal fabric, sedimentary structures and bed geometry. These pseudoconglomerates are characterized by oligomictic to polymictic limestone clasts of various shapes (i.e. flat to undulatory disc, blade and sheet), marlstone and/or grainstone matrix and various internal fabrics (i.e. intact, thrusted, edgewise and disorganized), as well as transitional boundaries. Limestone pseudoconglomerates formed as a result of soft‐sediment deformation of carbonate and argillaceous interlayers at a shallow burial depth. Differential early cementation of carbonate and argillaceous sediments provided the requisite conditions for the formation of pseudoconglomerates. Initial deformation (i.e. burial fragmentation, liquefaction and injection) and subsequent mobilization and disruption of fragmented clasts are two important processes for the formation of pseudoconglomerates. Burial fragmentation resulted from mechanical rupture of cohesive carbonate mud, whereas subsequent mobilization of fragmented clasts was due to the injection of fluid materials (liquefied carbonate sand and water‐saturated argillaceous mud) under increased stress. Storm‐wave loading was the most probable deformation mechanism, as an external triggering force. Subsequent re‐orientation and rounding of clasts were probably prolonged under normal compactional stress. Eventually, disrupted clasts, along with matrix materials, were transformed into pseudoconglomerates by progressive lithification. Soft‐sediment deformation is prevalent in alternate layers of limestone and mud(marl)stone and/or grainstone, regardless of their depositional environments. 相似文献
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华北地台与秦岭地槽构造关系初探 总被引：1，自引：1，他引：1
边界问题或构造关系问题,一直是地质学家最为关心的问题之一。华北地台与秦岭地槽构造关系的实质是洋壳与陆壳的矛盾统一和相互转化。中晚元古代时,秦岭地槽为洋壳演化区,华北地台为陆壳区,幸岭洋壳板块俯冲至华北陆壳板块之下:黑沟—铁炉子断裂相当俯冲带,其北洛南—栾川断隆是陆壳被改造而具陆缘弧性质;陆缘弧发展晚期在其南缘发育有弧前坳陷;陆缘弧之北的熊耳断坳则为弧后裂陷盆地;陆缘弧与弧后裂陷盆地之间的马超营—石门断裂为前陆断裂带。因此,秦岭地槽与华北地台的具体界线应以中晚元古代时大洋与大陆的分界线——黑沟—铁炉子断裂为准,而马超营—石门断裂仅为陆壳改造区内次级单位的分界. 相似文献
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大别山北麓石炭纪盆地沉积和构造研究 总被引：18，自引：0，他引：18
大别山加里东构造带北麓的石炭系为残留海盆地沉积 ,分布限制在潢川—固始—肥中断裂以南和信阳—商城—金寨—舒城断裂以北 ,保存在南翼向南倒转并有逆冲推覆构造的复式向斜中 ,中部被燕山期花岗岩侵入体破坏。排除构造重复 ,石炭系总厚 >2 0 0 9m (掩盖部分未计 ) ,按岩石地层单元分 5个组 ,各组之间均为断层接触。自下而上花园墙组为以复理石为代表的深水浊积扇和具有向上变细序列的陡坡扇沉积 ;杨山组为辫状河和滨岸辫状三角洲含煤沉积 ;道人冲组为辫状河、辫状三角洲、扇三角洲及滨浅海沉积 ;胡油坊组分布最广 ,为微咸水盆地陡坡扇、浊积扇沉积 ,有特征的复理石和滑塌沉积 ;杨小庄组为碎屑海岸含煤沉积。下统和上统的界限位于道人冲组中下部厚层砾岩的底部。古水流方向以自南指向北占优势 ,物源主要来自南侧的大别山区。石炭系下统砾岩为远源硅质正砾岩 ,含大量脉石英砾石 ,母岩为岩浆热液成因 ,现已无保存 ;上统砾岩为近源陡坡环境形成的复成分、多杂基的副砾岩 ,为浊积砾岩 ,其中脉石英砾石明显减少 ,含千枚岩和沉积岩砾石 ,母岩主要来自南侧的信阳群 /佛子岭群等。复理石、滑塌、浊积砾岩的存在表明石炭系具陡坡陆缘海活动大陆边缘的沉积特征 ,并发现有少量火山岩碎屑 ,可能形成于弧后盆地。稀? 相似文献
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滇东地区峨眉山地幔柱活动的沉积响应 总被引：3，自引：0，他引：3
对滇东地区峨眉山玄武岩下伏茅口组灰岩进行地层对比表明,地幔柱上涌导致的隆升开始于茅口期,表现为茅口组同沉积过程中断层差异升降形成的水下隆升;而现今看到的茅口组的地层减薄正是水下隆升形成的沉积地层厚度差异和沉积后地表隆升剥蚀的共同结果,但沉积后隆升的规模远远小于前人估算的千米级别。会东大桥-普格-布拖一带发育的砾岩表明峨眉山玄武岩喷发的多期次性和砾岩的水下泥石流成因,根据其分布范围划定了第一期岩浆喷发之后滇东地区的抬升剥蚀以西昌-巧家断裂和普雄-普渡河断裂为东界。根据上述地质证据,总结了滇东地区二叠纪的构造-沉积演化模型。 相似文献
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辽东复州湾中石炭世地层兼论华北地台中石炭统的划分 总被引：3，自引：0，他引：3
华北地台中石炭统本溪组一般仅代表中石炭世晚期沉积。从已知的几十个海陆交互相本溪组剖面来看,其中（虫筳）类生物群为Fusulina-Fusulinella带;牙形石生物群为Idtognathodus magnificus-Ⅰ.claviformis-Neognathodus ruondyi带,在整个华北地台均可依此进行对比。但在辽东半岛南缘的复州湾一带,中石炭世沉积特征却恰好与本溪剖面相反,下部层段以灰岩为主,上部层段以碎屑岩为主。下部含6层灰岩,（虫筳）类以Profusulinella的丰富种群为特征,可建立Profusulinella带,并可进而划分为3个亚带。牙形石则为Idiognathoides sinuatus-Ⅰ.corrugatus-Declinognathodus lateralis带。复州湾含灰岩为主的下部层段和本溪含碎屑岩为主的下部层段对比,依前者之生物组合建立本溪组下部复州湾段（c21）,代表华北地台中石炭世早期沉积;复州湾以碎屑岩为主的上部层段和本溪含5层灰岩的上部层段对比,依后者之生物组合限定为本溪组上部牛毛岭段（c22）,代表华北地台中石炭世晚期沉积。 相似文献
19.
MEI Mingxiang MA Yongsheng DENG Jun CHEN Huijun Key Laboratory of Lithospheric Tectonics Lithoprobing Technology of the Education Ministry China University of Geosciences Beijing Department of Oil-Fields China Petrochemical Corporation Beijing 《《地质学报》英文版》2005,79(3):372-383
In the Late Cambrian, the North China Platform was a typical carbonate ramp platform. The Upper Cambrian of the northern part of the North China Platform is famous for the development of bioherm limestones and storm calcirudites and can be divided from bottom to top into the Gushan, Changshan and Fengshan formations. In this set of strata, the deep-ramp mudstone and marls and the shallow-ramp packstones and grainstones constitute many carbonate meter-scale cycles of subtidal type. More tidal-flat dolomites axe developed in the Upper Cambrian of the southern margin of the North China platform, in which limestone and dolomite beds also constitute many carbonate meter-scale cycles of the peritidal type. These cycles are marked by a variety of litho-facies successions. There are regularly vertical stacking patterns of meter-scale cycles in long-term third-order sequences, which is the key to discerning such sequences. Third-order sequence is marked by a particular sedimentary-facies succession that is the result of the environment-changing process of deepening and shoaling, which is genetically related to third-order sea level changes. Furthermore, four third-order sequences can be grouped in the Upper Cambrian of the North China Platform. The main features of these four third-order sequences in the northern part of the platform can be summarized as follows: firstly, sequence-boundaries are characterized by drowning unconformities; secondly, the sedimentary-facies succession is generally constituted by one from deep-ramp facies to shallow-ramp facies; thirdly, a succession of “CS (?) HST” (i.e., “condensed section and highstand system”) forms these four third-order sequences. The chief features for the third-order sequences in the southern part of the North China Platform comprises: more dolomites are developed in the HSTs of third-order sequences and also developed more carbonate meter-scale cycles of peritidal types; the sedimentary-facies succession of the third-order sequences is marked by “shallow ramp-tidal flat”; the sequence boundaries are characterized by exposure punctuated surfaces. According to the changes for the third-order sequences from the north to the south, a regular sequence-stratigraphic framework can be established. From cycles to sequences, the study of sequence stratigraphy from litho-facies successions to sedimentary-facies successions exposes that as follows: meter-scale cycles that are used as the basic working unit actually are litho-facies successions formed by the mechanism of a punctuated aggradational cycle, and third-order sequences that are constituted by regularly vertical stacking patterns of meter-scale cycles are marked by sedimentary-facies successions. On the basis of the changing curve of water depth at each section, the curve of the relative third-order sea level changes in the late Cambrian of the North China Platform can be integrated qualitatively from changing curve of water depth. The correlation of Late Cambrian long-term sea level changes between North China and North America demonstrates that there are not only similarities but also differences, reflecting control of long-term sea level changes both by global eustacy and by regional factors. 相似文献